Can scientific evidence support using Bangladeshi traditional medicinal plants in the treatment of diarrhoea? A review on seven plants

Diarrhoea is a common disease which causes pain and may be deadly, especially in developing countries. In Bangladesh, diarrhoeal diseases affect thousands of people every year, and children are especially vulnerable. Bacterial toxins or viral infections are the most common cause of the disease. The diarrhoea outbreaks are often associated with flood affected areas with contaminated drinking water and an increased risk of spreading the water-borne disease. Not surprisingly, plants found in the near surroundings have been taken into use by the local community as medicine to treat diarrhoeal symptoms. These plants are cheaper and more easily available than conventional medicine. Our question is: What is the level of documentation supporting the use of these plants against diarrhoea and is their consumption safe? Do any of these plants have potential for further exploration? In this review, we have choosen seven plant species that are used in the treatment of diarrhoea; Diospyros peregrina, Heritiera littoralis, Ixora coccinea, Pongamia pinnata, Rhizophora mucronata, Xylocarpus granatum, and Xylocarpus moluccensis. Appearance and geographical distribution, traditional uses, chemical composition, and biological studies related to antidiarrhoeal activity will be presented. This review reveals that there is limited scientific evidence supporting the traditional use of these plants. Most promising are the barks from D. peregrina, X. granatum and X. moluccensis which contain tannins and have shown promising results in antidiarrhoeal mice models. The leaves of P. pinnata also show potential. We suggest these plants should be exploited further as possible traditional herbal remedies against diarrhoea including studies on efficacy, optimal dosage and safety.